The invention relates to the transmission of multimedia objects in a digital telecommunication system in general, and to the transmission of a start-up procedure (script) for multimedia software via a digital telecommunication system.
Multimedia means the presentation of synchronized, audiovisual items to the user. A standard has been created for handling multimedia software on an abstract level. The standard is designated as ISO/IEC 13522, it has 5 parts for the present, and in the following it will be referred to as the MHEG standard (Multimedia Hypermedia Information Coding Experts Group). In this standard, the multimedia software is defined as an entity formed by so called objects. These objects belong to object classes, which have been defined according to a certain syntax, and the members of the object classes are objects to which the class-specific definitions apply. Examples of object classes are links, action objects, composition objects, content objects and container objects. Some objects can be temporarily continuous, in which case they are called streams. In addition, objects can be multiplexed, whereby a multiplexed object consists of two or more streams, which are called component streams. These can again be multiplexed, or contain more streams.
The objects according to the MHEG standard are numbered, whereby they can be referred to by the numbers. The components of multiplexed objects are referred to be hierarchical series of numbers, for example, as in the standard MHEFG1, or by unique numbers without a hierarchy, as in the standard MHEG5. Let us assume, for example, that a multiplexed object A of the content class is denoted by number 1, as in FIG. 1, and it comprises a component stream B, the object number of which is 5 and which further comprises component streams, one of which, C, is denoted by 2. Thus the series of numbers, 1.5.2., according to the standard MHEG1, refers to the component stream C on the lowest level of the hierarchy, and at the same time indicates that the hierarchy has three levels. According to the standard MHEG5, each of the objects has a unique number without any hierarchical indications.
In order to produce a multimedia presentation by using objects according to the standard MHEG, a special tool is needed to handle or interpret the objects, organize the relations between them correctly by using the numerical references and control their presentation to the user. This tool is known as the "MHEG engine". It is generally implemented programmably, and its operation is defined in the standard MHEG on a general level.
Digital, broadcast-type telecommunication systems will become an important method for implementing massive data transfer, such as radio and television, in the future. Examples of digital broadcasting systems are the DAB and DVB systems (Digital Audio Broadcasting: Digital Video Broadcasting), but with certain assumptions, the invention can also be generalized to other types of systems. Because the present invention relates to the transmission of a reference system according to the MHEH standard and a start-up procedure for a multimedia presentation via a digital broadcasting system, in order to shed light on the background of the invention, the features of the DAB system that support that implementation of the invention will be described briefly in the following. The essential parts of the DAB system are defined in the standard ETS 300 401.
In according with FIG. 2, one signal stream transmitted by a transmitter according to the standard forms a DAB ensemble, which can contain a number of services E, F, G. In view of the user, each service corresponds to one radio channel of the present systems, and it consists of one or more service components H, I, J, K, L, M. A single service component can contain, for example, the audio part offered by the service, such as music, or a data part related to it, such as the lyrics of the song being played, or other information related to the service. One service component can belong to more than one service, like component J in FIG. 2. The service component which is the most essential in view of the serivce is called the primary service component, and other service components incorporated in the service are called secondary service components. The primary service component is often the audio part offered by the service, but it can also be a data part. The service can also contain many audio parts as service components. The connection between a service and its primary service component is denoted by a thick line in FIG. 2.
The information to be transmitted from the transmitter to the receiver over the radio interface of the DAB system is divided temporally into transmission frames S as shown in FIG. 3, the length of which frames can be 24 or 96 milliseconds, depending on the mode of operation. Each transmission frame S comprises three parts relating to the so called channels, which are: Main Service Channel (MSC), Fast Information Channel (FIC) and Synchronization Channel (Sync). The above mentioned service components E, F, G are contained in the service channel MSC, which is further divided into separate convolution-coded sub-channels O, P, Q, R as shown in FIG. 2. Each sub-channel can contain one or more service components. The mutual order of the service components and sub-channels is called multiplex configuration. The Fast Information Channel FIC contains the Multiplex Configuration Information MCI in particular, but it can also be used for transmitting other information quickly from the transmitter to the receiver. Like the service channel, it is divided into smaller parts as shown in FIG. 3, which are called Fast Information Blocks (FIB). The blocks further contain groups (FIG, Fast Information Group, not shown in FIG. 3). The synchronization channel Sync is used to control the transmission and reception operation of the system, such as the synchronization of the transmission frames.
A prior art solution, which would enable the transmission of a multimedia program consisting of objects organized by means of numerical references via a digital broadcasting system in a manner such that the properties of the broadcasting system itself are utilized by integrating them into the definitions of the multimedia program, is not known to exist.